<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    // let a = 10
    // let b = a
    // b = 30
    // console.log(a, b) // 10 30

    let obj1 = {name: '张三', age: 18}
    let obj2 = obj1
    obj2.name = '李四'

    console.log(obj1, obj2) 

  </script>
</body>
</html>